A.D.A. PD Prolog: A slow Prolog for MS-DOS systems.

A.D.A. Public Domain Prolog is a rather slow implementation of Prolog
for MS-DOS systems, originally a product of Automata Design Associates
(now defunct).
The distribution includes some sample expert systems, including Simon
Blackwell's "PIE" Truth Maintenance System, a few games written in
Prolog (including Towers of Hanoi), a few puzzles, and Ludwig J.
Schumacher's ATN-based natural language parser.
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*** Note: This and adapdpro are very similar. I haven't ***
*** the differences, and verified that the computer ***
*** algebra system runs in adapdpro, so I'm leaving this ***
*** version around for the time being. ***
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